The present invention generally relates to subsurface safety valves. More particularly, the present invention relates to a packer with an integral subsurface safety valve to be deployed to a subsurface location. More particularly still, the present invention relates to a packer having a conduit configured to bypass an integral safety valve housed therein.
Subsurface safety valves are typically installed in strings of tubing deployed to subterranean wellbores to prevent the escape of fluids, from one downhole zone to another. These zones can be production zones, investigation zones, intermediate zones, or upper zones in communication with the surface. Subsurface safety valves are most often used to prevent the escape of fluids from production zones to the surface, but can also be used to prevent fluids from escaping from one production zone to a second production zone. Absent safety valves, sudden increases in downhole pressure can lead to catastrophic blowouts of production and other fluids into the atmosphere. For this reason, drilling and production regulations throughout the world require safety valves be in place within strings of production tubing before certain operations can be performed.
One popular type of safety valve is known as a flapper valve. Flapper valves typically include a closure member generally in the form of a circular or curved disc that engages a corresponding valve seat to isolate one or more zones in the subsurface well. The flapper disc is preferably constructed such that the flow through the flapper valve seat is as unrestricted as possible. Usually, flapper-type safety valves are located within the production tubing and isolate one or more production zones from the atmosphere or upper portions of the wellbore or production tubing. Optimally, flapper valves function as large clearance check valves, in that they allow substantially unrestricted flow therethrough when opened and completely seal off flow in one direction when closed. Particularly, production tubing safety valves prevent fluids from production zones from flowing up the production tubing when the safety valve is closed but still allow for the flow of fluids (and movement of tools) into the production zone from above.
Flapper valve disks are often energized with a biasing member (spring, hydraulic cylinder, etc.) such that in a condition with zero flow and with no actuating force applied, the valve remains closed. In this closed position, any build-up of pressure from the production zone below will thrust the flapper disc against the valve seat and act to strengthen any seal therebetween. During use, flapper valves are opened by various methods to allow the free flow and travel of production fluids and tools therethrough. Flapper valves may be kept open through hydraulic, electrical, or mechanical energy during the production process. One popular form of mechanical device to counteract the closing force of the biasing member and any production flow therethrough involves the use of a tubular mandrel. A mandrel typically has an outer profile approximate to a clearance profile of the valve seat and is forced through the clearance profile to abut and retain the flapper disc in an opened position. With the mandrel engaged within the flapper valve seat profile, the flapper valve is retained in an open position and no accidental or unwanted closure of the flapper valve occurs.
When production is to be halted or paused, the mandrel is retrieved through the valve profile and the flapper valve is once again able to close through the assistance of the biasing member or increases in pressure within the production zone. Furthermore, the mandrel is preferably equipped with its own biasing member configured to retract it from the flapper valve seat in the event of a loss of power in the actuating means. An example of a flapper-type safety valve can be seen in U.S. Pat. No. 6,302,210 entitled “Safety Valve Utilizing an Isolation Valve and Method of Using the Same,” issued on Oct. 16, 2001 to Crow, et al., hereby incorporated by reference herein.
While the advantages of flapper-type safety valves are numerous, several drawbacks associated with their installation and use are also present. First and foremost, safety valves are typically installed as integral components of the production tubing assembly. As a result, an operation to install a safety valve to an existing string of production tubing typically requires the removal of the production tubing, the installation of a safety valve, and the re-installation of the production tubing. Such operations would need to be performed in circumstances where a downhole safety valve has never been installed (older production systems), where a safety valve needs to be replaced (repaired), or where additional safety valves, presumably to isolate additional production zones, are needed. Previously, apparatuses and methods to install a safety valve to or in existing tubing strings or wellbores accomplished the task at the expense of obstructing the passage of fluids and tools therethrough. A method and apparatus to install a subsurface safety valve having an unobstructed through bore to or in an existing string of tubing without necessitating the removal of that string of tubing is highly desirable.
Another disadvantage of existing safety valve systems is that after the flapper disc is closed, communication between the surface and the zone below is severed. Often, it is desirable to inject various fluids and substances into the isolated zone while leaving the flapper valve in a closed position. A safety valve assembly capable of allowing communication with the production zone when the valve is closed would be desirable to operators. Furthermore, when the flapper valve is open, any conduits deployed to a zone of interest therethrough obstruct the functioning of the safety valve. A safety valve capable of allowing communication with a production zone while the valve is in either open or closed position would be desirable to operators.
Finally, another disadvantage of existing safety valve systems is that the flappers often operate solely from the stored energy in the biasing member contained therein and from the pressure of the production zone below. No apparatus for manually closing the safety valve in the absence of one of these closing mechanisms exists. A safety valve manually closeable from the surface would likewise be highly desirable to those in the oilfield industry.